/*
 * ====================================================================
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package org.apache.http.entity.mime;

import java.util.*;

/**
 * The header of an entity (see RFC 2045).
 */
public class Header implements Iterable<MinimalField> {

  private final List<MinimalField> fields;
  private final Map<String, List<MinimalField>> fieldMap;

  public Header() {
    super();
    this.fields = new LinkedList<MinimalField>();
    this.fieldMap = new HashMap<String, List<MinimalField>>();
  }

  public void addField(final MinimalField field) {
    if (field == null) {
      return;
    }
    final String key = field.getName().toLowerCase(Locale.ROOT);
    List<MinimalField> values = this.fieldMap.get(key);
    if (values == null) {
      values = new LinkedList<MinimalField>();
      this.fieldMap.put(key, values);
    }
    values.add(field);
    this.fields.add(field);
  }

  public List<MinimalField> getFields() {
    return new ArrayList<MinimalField>(this.fields);
  }

  public MinimalField getField(final String name) {
    if (name == null) {
      return null;
    }
    final String key = name.toLowerCase(Locale.ROOT);
    final List<MinimalField> list = this.fieldMap.get(key);
    if (list != null && !list.isEmpty()) {
      return list.get(0);
    }
    return null;
  }

  public List<MinimalField> getFields(final String name) {
    if (name == null) {
      return null;
    }
    final String key = name.toLowerCase(Locale.ROOT);
    final List<MinimalField> list = this.fieldMap.get(key);
    if (list == null || list.isEmpty()) {
      return Collections.emptyList();
    } else {
      return new ArrayList<MinimalField>(list);
    }
  }

  public int removeFields(final String name) {
    if (name == null) {
      return 0;
    }
    final String key = name.toLowerCase(Locale.ROOT);
    final List<MinimalField> removed = fieldMap.remove(key);
    if (removed == null || removed.isEmpty()) {
      return 0;
    }
    this.fields.removeAll(removed);
    return removed.size();
  }

  public void setField(final MinimalField field) {
    if (field == null) {
      return;
    }
    final String key = field.getName().toLowerCase(Locale.ROOT);
    final List<MinimalField> list = fieldMap.get(key);
    if (list == null || list.isEmpty()) {
      addField(field);
      return;
    }
    list.clear();
    list.add(field);
    int firstOccurrence = -1;
    int index = 0;
    for (final Iterator<MinimalField> it = this.fields.iterator(); it.hasNext(); index++) {
      final MinimalField f = it.next();
      if (f.getName().equalsIgnoreCase(field.getName())) {
        it.remove();
        if (firstOccurrence == -1) {
          firstOccurrence = index;
        }
      }
    }
    this.fields.add(firstOccurrence, field);
  }

  @Override
  public Iterator<MinimalField> iterator() {
    return Collections.unmodifiableList(fields).iterator();
  }

  @Override
  public String toString() {
    return this.fields.toString();
  }

}

